Ken, thanks for the heads up on the Jamison cases. I'll bet that is the problem. I couldn't figure it out as I have some boxes of original .450 3 1/4" BPE, .450 nitro for black and .450 nitro from Kynoch fit very easily in all 3 rifles. I will try to contact Jamison (although they are under new owners) to see if they will make good.